Theoretical amplitudes and lifetimes of non-radial solar-like oscillations in red giants

TL;DR

This paper investigates the physical conditions under which non-radial solar-like oscillations in red giants can be detected, focusing on their amplitudes, lifetimes, and spectral signatures using theoretical models.

Contribution

It provides a detailed theoretical analysis of non-radial mode amplitudes and lifetimes in red giants, incorporating non-adiabatic pulsation and convection models, which was previously less explored.

Findings

Non-radial modes have different amplitudes and lifetimes depending on stellar evolution stage.

Theoretical predictions suggest observable non-radial modes in certain red giant conditions.

Mode heights in power spectra vary significantly with stellar parameters.

Abstract

Solar-like oscillations have been observed in numerous red giants from ground and from space. An important question arises: could we expect to detect non-radial modes probing the internal structure of these stars? We investigate under what physical circumstances non-radial modes could be observable in red giants; what would be their amplitudes, lifetimes and heights in the power spectrum (PS)? Using a non-radial non-adiabatic pulsation code including a non-local time-dependent treatment of convection, we compute the theoretical lifetimes of radial and non-radial modes in several red giant models. Next, using a stochastic excitation model, we compute the amplitudes of these modes and their heights in the PS. Very distinct results are found depending on the evolutionary status of the star.